Energy Flow in Ecosystems and Biogeochemical Cycles

Hierarchy of ecology Organism - individual living

thing Population- a group of the

same species Community – a group of

different species Ecosystem Ecosystem – all organisms as

well as nonliving things in an area

Biome - a major regional or global community of organism - can be as small as the microorganisms living on your skin or as large as the entire biosphere

What’s an Ecosystem? An ecosystem consists of all the organisms (biotic)

in a community and the environment (abiotic) with which they interact.

Biotic - living things plants animals, fungi, bacteria

Abiotic - non-living thingsMoisture, temperature, wind, sunlight, & soil

Biodiversity

The assortment, or variety, of living things in an ecosystem

KEYSTONE Species = a species that has an unusually large effect on its ecosystem

ProducerHerbivore

(primary consumer)

Detritivores(decomposers)

Carnivore(secondaryconsumer)

Energy flow

Energy flows THROUGH ecosystems – open system

Chemical cycling

Nutrients cycle WITHIN ecosystems – closed system

Get their energy from non-living sources and make their own food

Get their energy by eating living, or once living, resources, such as plants and animals

Break down organic materials into simpler cpmpounds

Energy Flow in Ecosystems

Almost all energy used in ecosystems comes from the sun

From there it flows through a food chain or web and exits the ecosystem in the form of heat, light, kinetic or chemical energy

A food chain is a sequence that links species by their feeding relation

A food web is a model that shows the complex network of feeding relationships and flow of energy within an ecosystem

Types of Consumers

Herbivores – eat only plants Carnivores – eat only animals Omnivores – eat both plants and animals Detritivores – eat detritis or dead and dying organic matter Decomposers - - detritivores that break down organic matter

into simpler compounds (example : fungi)

Decomposers

Energy pyramids show the efficiency of energy transfer between trophic levels

Generally 10% of energy is transferred Food chains never get beyond 4-5 trophic levels

Carnivores that eat secondary consumers

Carnivores that eat herbivores

Herbivores because they are the first consumer above the producer

The first , or bottom, trophic level

Consumers

Producers

Nutrientsavailable

to producers

Detritivores

Biogeochemical Cycle

Abioticreservoir

Biogeochemical Cycling of Nutrients The movement of a particular chemical through the

biological and geological, or living and non-living parts of an ecosystem.

Most ecosystems require a constant inflow of energy from the sun. In terms of matter, such as oxygen and carbon, the Earth is a closed system and it recycles its resources.

Water cycle Oxygen cycle Carbon cycle Nitrogen cycle Phosphorous cycle

Water Cycle

Solar energy drives the global water cycle – Precipitation– Evaporation– Transpiration

Water cycles between the land, oceans, and atmosphere

Forest destruction and irrigation affect the water cycle

Solar energy

Net movement ofwater vapor by wind

Evaporationfrom ocean

Precipitationover ocean

Evaporation andtranspiration fromland

Transportover land

Precipitationover land

Percolationthroughsoil

Runoff andgroundwater

Carbon Cycle

• Abiotic reservoirs = atmosphere, sedimentary rocks, dissolved carbon in oceans, and fossil fuels– Taken from the atmosphere by

photosynthesis– Used to make organic molecules– Decomposed by detritivores– Returned to the atmosphere by

cellular respiration

Photosynthesis

Burning offossil fuelsand wood

Primaryconsumers

Higher-levelconsumers

Cellularrespiration

Detritus

CO2 in atmosphere

Carbon compoundsin water

Decomposition

Global warming:CO2 lets sunlightthrough but retainsthe heat radiatedfrom Earth.

CO2 in theatmosphere

CO2

CO2 CO2

Human activities and naturalprocesses add CO2 to theatmosphere, increasing the effect.

Photosynthesis removesCO2 from the atmosphere,decreasing the effect.

Nitrogen Cycle

The nitrogen cycle relies heavily on bacteria

• Atmospheric N2 is not available to plants– Soil bacteria convert gaseous

N2 to usable ammonium (NH4

+) and nitrate (NO3-)

– Some NH4+ and NO3

- are made by chemical reactions in the atmosphere

Nitrogen in atmosphere (N2)

Nitrogenfixation

Detritivores

Decomposition

Assimilationby plants

DenitrifyingbacteriaNitrates

(NO3–)

Nitrifyingbacteria

Nitrogen-fixingbacteria in rootnodules of legumes

Nitrogen-fixingsoil bacteria

Ammonium (NH4)

80%

Phosphorus Cycle

Depends on the weathering of rock

• Phosphorus and other soil minerals are recycled locally

• Weathering of rock adds PO43- to

soil– Slow process makes amount of

phosphorus available to plants low

Runoff

Sedimentation